The present invention relates generally to electrical connectors and more particularly relates to polarization keys therefor.
Separable electrical connectors having corresponding electrical contacts are well known in the art. Typically, these electrical connectors are provided with polarizing keys or other polarization devices in order to prevent an improper mating of male and female electrical connectors. For example, the key of one connector may be of a three-sided configuration which mates with a corresponding three-sided key of another connector when properly oriented therewith, to form a resultant hexagonal arrangement.
The keys or polarizing members are mounted on the separable electrical connectors so that axially extending projections of one connector may mate with proper ones of the other connector during a joining of the connectors. Various arrangements are known in the art for mounting and polarizing members on the electrical connectors. Representative patents disclosing arrangements for mounting polarizing members on electrical connectors include U.S. Pat. Nos. 3,582,867 issued to Thompson et al on June 1, 1971; 3,714,617 issued to Bright et al on Jan. 30, 1973; 3,177,461 issued to Hagan et al on Apr. 6, 1965; 3,675,185 issued to Ruehlemann et al on July 4, 1972; and 3,426,315 issued to DeTar on Feb. 4, 1969.
All of the known methods for mounting the keys or polarization members on the electrical connects are undesirable for one or more reasons. For example, in one instance a key has been provided with a hexagonally-shaped base which seats within a corresponding hexagonally-shaped cavity in the connector, thus providing six selective positions of adjustment for the key. The key is fixed within the cavity by a pair of retaining pins which each extend through the connector housing and through the annular depression of the key. In particular, the connector housing includes two side-by-side pairs of aligned pin-receiving holes. Each pair of aligned holes intersects the key-receiving cavity and is adapted to receive one of the retaining pins by a pressure fit.
The hexagonal base of the key is interrupted by an annular grove. The grove is slightly wider than the diameter of the largest retaining pin. The minor diameter of the grove is less than the distance between the pairs of pin receiving holes in the connector housing. For each of the selected key positions the continuous grove provides an aperture for the retaining pins. Thus, each retaining pin can be installed within one of the pairs of aligned holes, with its middle section disposed within a grove of the key base. Accordingly, the key is held against axial displacement relative to the housing. Rotational displacement is limited by seating the hexagonally-shaped key into a hexagonally-shaped cavity in the housing previously described.
It is necessary that close tolerances be maintained for the holes and retaining pins thereby requiring significant fabrication cost and time. In this regard, the dimension of the holes for each retaining pin can readily be drilled to only one or two-thousandths of an inch tolerance. Nickel plating which is subsequently provided on the electrical connector has a thickness ranging from about one to three-thousandths of an inch. If the holes for receiving the retaining pins are initially too small or the subsequent plating is too thick, the holes must be redrilled and individually coated with a material, for example, gold iridite. Of course, it is preferable to have a fully unbroken nickel plating on the electrical connector if possible, and furthermore it is desirable to avoid the expense involved with redrilling and recoating the holes.
The use of retaining pins to maintain the key on the electrical connector is also desirable since the key cannot then be readily removed and repositioned. Such a removal and repositioning of the key is oftentimes desirable in order to permit one electrical connector to mate with a different electrical connector.
In other known arrangements for mounting a key or polarizing member on an electrical connector, the key is provided with a threaded shaft which extends completely through the electrical connector. A nut is then threaded onto the end of the shaft to retain the key on the connector. In such an arrangement, the nut must be rotated which typically requires that the connector be disassembled from a daughterboard before the key can be removed.
In a further known arrangement, and depicted herein in connection with FIG. 3, a screw may be loosely positioned within a bore of the connector for threadably securing the key in place. However, the screw is to receive a tool from an end thereof which is opposite the end to which the key is connected. Accordingly, the tool-receiving side of the connector must be accessible to the tool which is not always possible or convenient.
In another known arrangement, the key is frictionally received within a depression of the electrical connector. In such an arrangement, the keys may have a tendency to separate from the electrical connector inadvertently.
In still another arrangement, a retaining ring axially fixes the key with respect to the electrical connector. Such a retaining ring is difficult to position and remove.
Prior to the actual installation of the electrical connectors, it is desirable to perform tests therein in which the connectors are repeatedly detached and recoupled. During such operations, there exists the danger that elements of the contact assembly may become bent if the contacts of one connector are not truly aligned relative to those of the other connector. It has been known in the case of some types of connectors, other than edgeboard connectors, to employ leader sleeve and leader pin elements which are fixedly connected to respective connectors and which mate when the connectors are joined, to assure that proper alignment between the contacts occurs. However, in order to compensate for dimensional tolerances, the sleeve is usually oversized to assure that mating between the pin and sleeve can occur when slight misalignment of such sleeve and pin elements exists. Of course, the presence of such oversizing somewhat defeats the original purpose of providing the leader pin and sleeve since the sleeve and pin elements may thus permit slight misalignment to occur between the connectors.
It is, therefore, an object of the present invention to minimize or obviate problems of the sort discussed previously.
It is a further object of the present invention to provide novel methods and apparatus for properly orienting and aligning electrical connectors.
It is another object of the present invention to provide a releasable key arrangement for an electrical connector wherein a polarization key is readily attached to a support member by a threaded retaining member.
Another object of the present invention is to provide a releasable key arrangement wherein removal of the key from a support member may be achieved by rotation of a threaded retaining member which is rotatably mounted on the support member or on the key.
Yet still another object of the present invention is to provide a key arrangement for an edgeboard connector wherein a key may be rigidly mounted on the edgeboard connector but readily released when desired to permit a repositioning of the key on the edgeboard connector.
It is an additional object of the invention to provide novel methods and apparatus which enable a leader pin and leader sleeve to be automatically aligned in response to the interconnection of associated connectors and thereafter maintained in alignment.